The present invention relates to methods of making fluorinated alcohols. More specifically, the present invention provides processes for producing fluorinated alcohols from non-perfluorinated fluoroolefins.
Fluorinated alcohols find use in a wide variety of applications. For example, fluorinated alcohols are used as pharmaceuticals, inhalation anesthetics, herbicides, polymers, refrigerants, etchants, lubricants, heat transfer fluids, and the like. See, for example, Banks, R. E. et al xe2x80x9cOrganofluorine Chemistry, Principles and Commercial Applications xe2x80x9d Plenum Press, New York and London, 1994, which is incorporated herein by reference. In particular, fluorinated butanols are desirable for use in the syntheses of pharmaceutical drug candidates and for use as solvents for photographic sensitizing dyes and in epoxidation and Diels-Alder reactions. See, for example, U.S. Pat. No. 3,756,830, issued to Polaroid Corp.; Van Vliet, M. C. A., et al., Fluorinated alcohols: effective solvent for uncatalyzed epoxidations with aqueous hydrogen peroxide, Synnlett, vol. 2, (2001), pp. 248-250; and Cativiela, C., et al., Fluorinated alcohols as solvents for Diels-Alder reactions of chiral acrylates Tetrahedron:Assymetry, 4(7), (1993), pp. 1613-18, each of which is incorporated herein by reference.
A number of processes for the preparation of fluorinated alcohols, in particular fluorinated butanols, using perfluorinated compounds as starting materials are described in the art. For example, Hazeldine et al., J. Fluorine Chem. 1985, 28, 291-302, incorporated herein by reference, describes the in vacuo reaction of hexafluoropropene with methanol under thermal, photochemical, and peroxide-initiated conditions to form fluorobutanols of the formula CF3CHFCF2CR1R2OH, wherein R1 is hydrogen and R2 is hydrogen, methyl, propyl or trifluoromethyl; or R1 is methyl and R2 is methyl or ethyl. U.S. Pat. Nos. 6,187,969 and 6,294,704, both issued to Daikin Industries and incorporated herein by reference, describe the preparation of fluoropropanols and fluorobutanols by reacting tetrafluoroethylene or hexafluoropropylene with methanol in the presence of a free radical generator and under a relatively high pressure (from about 0.2 MPa to about 1.2 MPa).
The present inventors have come to appreciate that such prior art methods for making fluorinated alcohols from perfluorinated starting materials are disadvantageous for several reasons. One disadvantage associated with the prior art methods is that such methods require subjecting a fluorinated-alcohol-forming reaction mixture to either very high pressure or very low pressure (e.g. under vacuum in sealed quartz vessels), making the reaction difficult and/or expensive to scale-up for industrial use. In order to create high pressure or vacuum, the reactions of the prior art methods must be conducted in sealed reactors, such as autoclaves, capable or maintaining high or low pressures without leaking. As the prior art reactions are scaled up, larger sealed reactors capable of creating and withstanding high or low pressure become necessary. Providing such large scale reactors which overcome the inherent problems of avoiding leaks on such large scale equipment tends to be highly expensive as compared to large scale vessels which need not be sealed.
The prior art methods are also disadvantageous in that many of such methods require heating reaction mixtures containing peroxides. Because peroxides tend to be explosive at elevated temperatures, the heated peroxide-containing reactions of the prior art tend to be highly, if not prohibitively, dangerous to conduct, especially on larger commercial scales.
Yet another disadvantage associated with prior art methods is the relatively long reaction times required in such methods.
Recognizing these and other drawbacks of the prior art, the present inventors have perceived a need for a new, efficient and more desirable method for producing a wide range of fluorinated alcohols. These and other objects are achieved by the present invention as described below.